Re: passing a variable to a spec file from rpmbuild command line

On 11/11/07, [email protected] <[email protected] >
wrote:
>
> Hi all,
>
> I have a question on passing a variable to a spec file.
>
> Say, for example, I have a feature, and i want to pass information to the
> spec
> file to either enable or disable that feature, so that the spec file can
> then
> pass to configure appropriayte option to enable/disable the cooresponding
> feature.
>
> I've seen some references to "--with abc" or "--without abc"
>
> what exactly happens here ? is there a variable that I can reference
> inside the
> spec file to see if "abc" was mentioned with either "--with" or
> "--without" ?
> and how might I reference that variable?





What happens is that a macro is conventionally defined.


Here's what happens with "--with abc"


This line in /usr/lib/rpm/rpmpopt-X.Y
    rpmb    alias --with            --define "_with_!#:+       --with-!#:+"


causes a macro "_with_abc" to be defined with value "--with-abc".


The option "--with abc" is exactly the same as typing
    --define '_with_abc --with-abc'



I also have seen the syntax:
>
>         %{?variable:1}
>
> I think this is testing "variable" and if the "variable" in question
> doesn't
> exist (hasn't been defined), then return a "1" for the test value. Is this
> true
> ? and what gets returned if the variable IS defined? the variables value ?



Not quite. The construct expands to "1" if variable is defined, ""
otherwise.


If you wanted to use the defined value (if it exists) or a default value (if
not),
then that could be done with this (kinda clunky) construct.
    %{?variable}%{!?variable:1}


The construct %{?variable} expands variable if defined, otherwise "" is the
value.

Since one is often using 1/0 as TRUE/FALSE with %if statements, then


   %if %{?variable:1}0


can be used. The expansion is either "10" or "0" depending on whether
variable is defined (or not),
and the %if is then either TRUE or FALSE.

I've searched high and low all over the net as regards to the intracies of
> user
> defined variables, and the answers to the above questions have been
> eluding me.
> I'd be grateful for answers and/or pointers/urls to documentation.





You can define any macro you please using --define 'name value' from the
CLI.
Macros are just a means to substitute strings recursively.


Macros are distantly related to how gcc parses CLI arguments. Many ideas
(but not code)
were borrowed and reworked.

hth

73 de Jeff

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